Sleep disordered breathing is a serious disorder characterized by complete cessation of respiration during sleep. Sleep disordered breathing results in sleep fragmentation and hypoxemia during the night, which can lead to cardiac arrhythmias, nocturnal hypertension, nighttime confusion and neuropsychological impairment. This disorder is extremely common in elderly people, yet little is known about the natural history, clinical implications or risks of this disorder. Preliminary data suggest that this disorder may be more prevalent in younger African-Americans, but older African-Americans have not been studied. This study proposes to continue following the natural history and progression of sleep disordered breathing in elderly men and women every two years by rerecording their sleep with unattended monitoring (modified Respitrace/Medilog recorder with portable oximetry). Each will.be-interviewed about sleep, medical history, mental functioning, mood and quality of life. These men and women have already been studied at least twice at two year intervals. These data will allow the testing of whether a) cognitive functioning will be inversely related to the amount of respiratory disturbance; b) quality of life will be inversely related to the amount of respiratory disturbance. This study will also recruit older African-Americans to test whether a) respiratory disturbance indices are higher in older African-Americans than in older Caucasians; b) blood pressure at night in older African-Americans with sleep disordered breathing declines less than in older Caucasians with this disorder; c) survival times for older African-Americans with sleep disordered breathing are shorter than for elderly Caucasians. This study also will continue to follow older volunteers to determine more fully the relationship between sleep disordered breathing and mortality. By examining these questions, the significance for older Caucasians and older African-Americans, of having sleep disordered breathing and the need for treatment may be better understood.